While both the UBR(R) and STR(R) come with TYPE 1 push-button QD swivel sockets pre-installed on the left side of the stock"" this Sling Mount Kit - TYPE 2 can be installed on the opposite side to add additional push-button QD Sling Swivels or our own Magpul(R) QDM. Additionally"" for running ambidextrous sling swivels on the SGA(R)"" MOE(R) Rifle"" MOE(R) Fixed Carbine"" MOE(R) AK"" Zhukov-S"" Hunter 700"" and Hunter X-22 Stocks"" this TYPE 2 Kit must be utilized in conjunction with the optional TYPE 1 Kit. Heavy-duty black phosphatized steel construction easily installs with the UBR or STR's original hardware"" or with the hardware included with the TYPE 1 Kit. Swivels not included.